The invention relates to resistivity-switching metal oxides, specifically nickel oxide and cobalt oxide.
These materials can be reversibly switched between two or more stable resistivity states by application of appropriate electrical bias pulses. These resistivity states can correspond to data states of a nonvolatile memory cell.
Nickel oxide and cobalt oxide may be formed in high-resistivity states. In some embodiments it has been found that the first pulse required to perform the switch from the initial high-resistivity state to a lower-resistivity state can be larger than the pulses required for subsequent switches.
Large-amplitude pulses have many disadvantages. It would be advantageous to avoid the need for a large-amplitude pulse to perform the initial resistivity switch. It would further be advantageous to reduce the current or voltage required for subsequent switches between resistivity states.